The present invention relates to the field of chemistry and, specifically, to the technology of organic synthesis; namely to the production of acetone obtained together with phenol during the decomposition of cumene hydroperoxide.
In addition to the basic products, which are acetone and phenol, an entire series of impurities having an adverse effect on the quality of the end product forms during the oxidation of cumene and subsequent decomposition of cumene hydroperoxide. After neutralization, acetone and phenol, the decomposition products of cumene hydroperoxide are fed to a fractionation column, in which they are separated into acetone raw material and phenol raw material fractions. Then, depending on the purification system used, the acetone raw material and phenol raw material fractions enter the appropriate stages of isolation and purification.
A method is known for purifying acetone raw material comprising subjecting the decomposition product to purification in two rectification columns wherein the acetone treated in the first rectification column is sent to the second rectification column, and purified acetone is discharged from the top of the second rectification column as a commercial product (see U.S. Pat. No. 3,215,745).
It is known, however, that use of simple distillation methods alone to purify acetone raw material is not completely effective since impurities, specifically, aliphatic aldehydes, olefins and a whole series of other impurities, remain in the treated acetone product, reducing its purity and quality.
A number of chemical treatment methods involving alkali metal hydroxides are known that are effective in causing low-boiling aldehydes to condense to high-boiling aldols that are then removed from the acetone by ordinary distillation (see, for example, U.S. Pat. Nos. 4,722,769 and 4,340,447). These references each disclose different processes for purifying acetone in the presence of an alkaline agent. The aldol derivatives formed are thermally unstable and decompose in the reboiler of the distillation column, thus producing low-boiling aldehydes. Both methods produce product (commercial) acetone having KT-Test values that are lower than desired.
A method for purifying acetone in which distillation of acetone raw material is carried out in three rectification columns in sequence is also known (see, for example, Canadian Patent No. 1016100). In this process, the second column is operated under reduced pressure, which increases operating costs and decreases operating capacity.
There is a need to provide a simple and flexible method for further purifying acetone (to reduce the levels of impurities) without regard to the quality of the acetone raw material.